1. Field of the Invention
The present invention relates to a vibration proof or preventing damper, and more particularly to a vibration preventing technology suitable for equipments such as automotive audio systems or portable personal computers provided with a reading mechanism for reading data from a recording medium such as a CD, a CD-ROM and a hard disc in a non-contact manner.
2. Description of the Related Art
In the equipment provided with such non-contact type reading mechanism for the recording medium in which the vibrations should be prevented, a variety of vibration proof means have been conventionally provided in order to attenuate vibrations that adversely affect the readout of the data. FIGS. 5 and 6 schematically show reproduction devices used in, for example, personal computers or automotive audio systems. These reproduction devices are adapted to optically read out music data from a music CD and reproduce them. A mechanical chassis 3 provided with a motor 2a, an optical pickup 2b, a disc table 2c and the like is installed in an interior of a casing 1. The mechanical chassis 3 is supported elastically within the interior of the casing 1 by vibration preventing dampers 4 and 5 in a vibration preventing manner so that the vibration hardly would be transferred.
Such vibration preventing dampers 4 and 5 are typically shown in two types as shown in FIGS. 5A to 5C and 6A to 6C. The device shown in FIGS. 5A to 5C is an insulator type damper in which the vibration preventing damper 4 is composed of an elastic cylindrical member 4a made of rubber or the like and each of the engagement recess grooves 4b provided circumferentially on a side surface is fitted inside of a C-shaped engagement projection 3a of the mechanical chassis 3. Then, when amounting screw N1 is inserted into the hollow interior of the elastic cylindrical member 4a and threadedly fixed to the casing 1, the mechanical chassis 3 are supported elastically at a plurality of positions by the vibration preventing dampers 4 within the casing 1 in a vibration preventing manner.
Further, the device shown in FIGS. 6A to 6C is of a type in which viscous fluid is sealed in the interior and the vibration is attenuated by utilizing the viscous fluid resistance of the viscous fluid. This vibration preventing damper 5 has a bottomed cylindrical agitating sleeve portion 5a and is provided with a damper housing 5e consisting of an elastic wall portion 5b to elastically deform in the three-dimensional directions to suppress the floating movement of the agitating sleeve portion 5a and to expand so as to surround the agitating sleeve portion 5a and a circumferential all portion 5d made of a hard resin, fixed at one end to an elastic wall portion 5b and having an outward flange 5c at the other end. A viscous fluid 5f is filled in the interior of the damper housing 5c and sealed by fixing a lid member 5q to the damper housing 5e to form the vibration preventing damper 5. Then, when the vibration preventing damper 5 is mounted on the mechanical chassis 3, a support rod 3b projecting from the mechanical chassis 3 is inserted into the agitating sleeve portion 5a and held thereat. Further, when the vibration preventing damper 5 is mounted on the casing 1, a mounting screw N2 is inserted into a screw hole formed in the lid member 5g and then screwed to the casing 1. Thus, the mechanical chassis 3 are elastically supported at a plurality of positions by the vibration preventing dampers 5 within the interior of the casing 1 in the vibration preventing manner.
As described above, the excellent vibration attenuating effect by the vibration preventing dampers 4 and 5 is exhibited, whereby the vibration would be hardly transferred from the casing 1 from the mechanical chassis 3 elastically supported within the interior of the casing 1. However, there are some problems. One of them is a degradation in working efficiency when the chassis is mounted on the casing 1.
Namely, in any conventional example shown in FIGS. 5A to 5C and 6A to 6C, the mechanical chassis 3 and the vibration preventing dampers 4 and 5 are formed into separate pieces. For this reason, in order to complete the mounting work between the mechanical chassis 3 and the casing 1, in the case of the conventional example shown in FIGS. 5A to 5C, in addition to the mounting work of the vibration preventing damper 4 to the mechanical chassis 3, a screwing step using a much larger number of mounting screws N1 is required. Accordingly, the number of steps is increased and the steps are troublesome. Further, in the case of the conventional case shown in FIGS. 6A to 6C, in addition to the mounting work between the vibration preventing damper 5 and the mechanical chassis 3, it is necessary to perform the screwing work between the vibration preventing damper 5 and the casing 1 using a plurality of mounting screws N2. Further, in this case, a large number of steps are required.
Further, in addition to such degradation in working efficiency, there is a problem in coping with a miniaturization for the mounting space. The tendency of miniaturization of the equipment, i.e., the demand for downsizing is increasing day by day. Such demand is remarkable in the field of automotive audio systems or notebook personal computers. Namely, in the case of the conventional examples shown in FIGS. 5A to 5C and 6A to 6C, if the casing 1 is miniaturized, correspondingly, the mechanical chassis 3 is also to be miniaturized. As a result, the mounting space for the vibration preventing dampers 4 and 5, that is, a gap between the inner wall of the casing 1 and the mechanical chassis 3 is also narrowed. Accordingly, in order to meet this miniaturization requirement, in the case of the vibration preventing damper 4 shown in FIGS. 5A to 5C, it is inevitable to reduce a height of the cylindrical elastic member 4a. If so, there are some cases where it is impossible to realize the vibration attenuation performance that is required. Further, in the case of the vibration preventing damper 5 shown in FIG. 6, if the circumferential wall portion 5d is more decreased and the agitating sleeve portion 5a is more shortened to thereby decrease the filling amount of the viscous fluid 5f for the miniaturization, it is possible to meet the requirement for the miniaturization. However, also, in this case, it is inevitable to sacrifice the vibration attenuation performance.